The present invention relates generally to integrated circuits, and more particularly, to an integrated circuit layout with a mesh structure and configurable buffer circuits.
An integrated circuit (IC) includes a plurality of metal layers used to route signals, as well as power and ground, between circuit elements. The metal layers are interconnected with vias. Prior to fabrication, the IC is designed and laid out. The layout designing process has two phases, a pre-mask phase and a post-mask phase. The pre-mask phase includes IC layout designing before generation of a photo mask corresponding to the IC layout. The post-mask phase includes IC layout designing after generation of the photo mask. One photo mask may include 60-80 individual masks. Transistor masks have the smallest feature size and are therefore the most expensive, whereas metal layer masks have large feature sizes and are therefore less expensive.
Engineering change orders (ECOs) are last-minute design changes implemented during both the pre-mask and post-mask phases to rectify design errors found during testing. The ECOs are often implemented using spare cells present in the IC layout by connecting some of the spare cells with the operational cells, which of course requires routing signals between the spare cells and the operational cells. The operational cells and spare cells may be present in a single semiconductor platform, or they may be present in different platforms. As used herein, the term platform means a logic block or pre-defined circuit that has defined boundaries, such as a processor core or a memory (e.g., DDR memory).
When the operational cells and the spare cells used for an ECO are within the same platform, it is relatively easy to route the connections. However, when the operational cells and spare cells used to implement an ECO are located in different platforms, more routing resources are required to route the signal(s) between platforms.
It would be advantageous to have an IC layout that facilitates routing of signals from between platforms through fewer metal layers.